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Can You Use a 40v Battery in a 20v Tool? (Explained)

Electrical appliances and machines are used by us almost everyday and have become an inseparable part of our lives. 

However, these electric components require delicate care and are sensitive to changes – which means you should be careful while using power sources of different voltage ratings than specified. 

The extract below details the usage of different rated voltage sources and their implications.

Can you use a 40v battery in a 20v tool?

You should not use a 40V battery in a 20V tool because of the different power supply capabilities both of them have. This will cause the 20V tool as well as the 40V battery to be damaged due to voltage overload and therefore cause the tool to become permanently unusable.

Batteries or battery packs are often used to operate electrical appliances and tools ranging from trimmer to even leaf blowers. 

Each of these appliances have different power requirements – which is why they have specific voltage rated battery packs for them and don’t work with just any battery. 

Batteries with higher voltages have a higher power capacity and thus can deliver greater strength to the appliances – however, not all appliances can withstand such power and thus there are different rated batteries for them.

Since 40V batteries have a greater power rating, it might give the impression that they are better than lower rating batteries such as 20V, however using them on tools that are 20V rated is not a good idea. 

The reason being that those motors are smaller and meant for lightweight functions – which are not built to handle the power of a 40V battery.

Although you can use batteries of different capacities which have different amp hours interchangeably, you need to make sure that those batteries have a 20V rating. 

Higher voltage rating batteries such as 40V are not suitable for tools with a lower rating such as 20V because this higher voltage would overload the tools and their internal components and cause permanent damage to both the tool and the battery.

But in some cases, some tools which are rated 20V can also function well on 40V but that has to be explicitly stated on the tool’s manual, otherwise the tool would be damaged. 

Another way to use a 40V battery on a 20V tool is if you could modify the battery’s circuitry to give an output of 20V.

Worx ,Black and Decker, Hart as well as Dewalt have batteries of 40V ratings, but it should be kept in mind that none of them should be used on a 20V tool because that would not only damage the batteries but also fry the tool’s circuitry.

Is 40V more powerful than 20V?

Batteries or battery packs are used to supply power to electric appliances and devices according to each of their requirements. 

The voltage rating on each battery or battery pack signifies the amount of power they can deliver – the higher the voltage rating, the greater the power it can deliver.

40V batteries are able to supply almost twice the power of 20V batteries which can supply, therefore both of them are used for different appliances which have varying power demands. 

Although 40V is more powerful than 20V, that doesn’t mean that you can use the 40V battery everywhere instead of the 20V ones.

If a tool has 20V power demands, using 40V on it would be too excessive for it to handle and thus lead to damage. Similarly, using a 20V battery on a tool of 40V power demands then it will be underpowered and not work as intended.

4 reasons why you should not use a 40v battery in a 20v tool

Electrical appliances and tools are excessively sensitive and should be handled with care, especially when you are dealing with their power source. Therefore, below discussed are the several reasons why you should not use a 40V battery in a 20V tool:

40V supplies greater power:

40V batteries supply a greater power which is double the power demands the 20V tool has. A 20V tool works effectively and efficiently with a 20V power source and thus adding a 40V power source doesn’t significantly improve its functionality in the long run. 

Thus, using a 40V supply is excessive for a 20V tool and is unnecessary.

The battery will be damaged:

Batteries are designed to supply power to the tool or appliance according to their power demands and continue to do so until their power is completely depleted. 

This happens if you are using the appropriate battery for each tool, however if you use a  higher rating battery such as a 40V battery on a 20V tool – the battery will oversupply power and cause the tool to overload. 

This in turn will prevent the battery from supplying power effectively and thus damage it.

The tool’s circuitry will become fried:

If 40V batteries are used on a 20V tool, the battery will be supplying more power than the demand of the tool, therefore this voltage overload will cause some of the sensitive circuitry in the tool to heat up quickly and lead them to become burnt. 

The tool might get permanently damaged:

If the previous problem occurs and many important components of the tool have burnt, then those parts may be irreplaceable. If that is the case, then the tool will be permanently damaged and you will have to buy a new one.

What happens when you use a 40v battery in a 20v tool?

A 40V battery provides excessive power to a 20V tool, therefore this would cause the tool to have a voltage overload. This overload would let the tool function at its maximum potential but at the cost of its lifespan.

Because prolonged use of a 40V battery on a 20V tool would cause the inner circuitry of the tool to heat up quickly and thus eventually lead the circuits to burn. 

In addition to this, the overload would also prevent the battery from supplying power to the tool effectively and thus cause the battery to be internally damaged as well.

If this effect continues, the battery will be permanently damaged and the tool will have most of its circuitry damaged to prevent it from ever functioning. 

What is the difference between 20V and 40V battery?

There are some core differences between the 20V and the 40V battery which makes them significantly different from each other and makes them suitable for use in different tools or appliances. Below stated are the main differences between a 20V and a 40V battery:

Difference in supply power:

The voltage rating of a battery determines how much power a battery can supply to a tool or an appliance. Higher voltage ratings indicate higher power output from the battery and vice versa for lower voltage ratings. 

Which means the 40V battery has a higher power output compared to the 20V battery.

Difference in charging time:

The 40V battery has a higher power delivery capacity which means it must have a greater capacity to store such power compared to 20V batteries. This would mean that the 40V batteries need much longer time to fully charge up compared to 20V batteries. 

This difference in charging time makes it more convenient to use 20V batteries for quicker use while 40V ones give a longer service at a cost of longer charging time.

Difference in application: 

Due to the varying power supply capabilities, speed of power supply as well as duration of power supply, both types of batteries have different applications that are best suited for them.

40V batteries are usually used on tools or appliances that have higher power demand and need to be used for a while, meanwhile 20V batteries are commonly used on tools that have lower power demands and are used for a short span of time.

Are Hart 20V and 40V batteries interchangeable?

20V and 40V batteries are fundamentally different from each other due to their vastly differing voltage rating which allows them to supply power catering to different types of appliances. 

The 20V batteries are usually used for lightweight tools that have low power  demands, while 40V batteries are used in heavy, power-hungry tools.

Commonly, 20V and 40V batteries are not interchangeable without having to tweak and change the internal circuitry of the battery to supply 20V. 

However, in the case of Hart’s battery-powered tools – you can use the 20V and 40V batteries interchangeably within the system.

Final Thoughts

Because of the differences in power supply capacities, you should not use a 40V battery in a 20V tool. As a result of the voltage overload, both the 20V tool and the 40V battery will be harmed, rendering the tool permanently inoperable. 20V tools have a limitation of 20V, thus 40V would cause harm.